Circular knitting machine having a latch lifter and method of operating same



May 26, 1953 G c PARHAM 2,639,596

CIRCULAR KNITTING MACHINE HAVING A LATCH LIFTER, AND METHOD OF OPERATING SAME Filed March 28, 1950 3 Sheets-Sheet l 40/ /v /D a 9 I I nil l Y 500 Q GD /0 INVENTOKL. 69am? QMM/w P416664 BY HIS ATTORNEYS May 26, 1953 Filed March 28, 1950 G. c. PARHAM CIRCULAR KNITTING MACHINE HAVING A LATCH LIFTER, AND METHOD OF OPERATING SAME 5 Sheets-Sheet 3 Filed March 28. 1950 5 .5. 5/?0/46? 'Qzrzmvp 89PM 1 -BY H/S ATTORNEYS Patented May 26, 1953 2,639.596 ICE CIRCULAR KNITTING MACHINE HAVING A LATCH LIFTER AND METHOD OF OPER- ATING SAME Grover O. Parham, Dalton, Ga., assignor to Scott 8: Williams, Incorporated, Laconia, N. H., a corporation of Massachusetts Application March 28, 1950, Serial N 0. 152,340

16 Claims. 1

This invention relates to a circular knitting machine having a latch lifter, and to a method of operating same, and more particularly to a latch lifter adapted to assist the casting off of transferred loops. In making ladies hosiery on automatic circular knitting machines that have independent latch needles, it is desirable tomake a turned welt. For this purpose transfer bits are used to take loops at the beginning of the knitting and to transfer them back to the needles after the welt has been knitted. When these loops have been transferred back to the needles preparatory to knitting them into the fabric, they lie loosely around the needle shanks and are so slack that they sometimes get caught on the ends of the latches and get into the hooks of the needles instead of being cast oif with the old stitch. When this happens the loops are not cast off until a subsequent revolution of the machine. undesirable appearance to the welt. One of the objects of the present invention is to prevent the formation of such a ragged-appearing welt in circular knit stockings. Another object is to prevent a needle latch from becoming caught in any loop on a needle shank.

It is characteristic of a machine made in accordance with my invention that the latch lifting blade functions at a point spaced from the stitch cam. I have found that if the latches are lifted part way by the blade as soon as the welt loops are transferred to the needle shanks, the centrifugal force created by the rotary movement of the needle cylinder in the modern automatic hosiery knitting machine will prevent the latches from dropping down again when they get beyond the lifter blade. For this reason the end of the blade is located some distance from the casting off point of the stitches:

In the drawings:

Figure 1 is a perspective skeleton view of the top of a needle circle, sinker cap and associated parts of a Scott 8: Williams independent latch needle circular knitting machine made in accordance with my invention, showing the latch lifter blade in operation;

Figure 2 is a perspective View of a few needles and fabric loops seen from the center of the dial of Fig. 1, showing the effect of the latch lifter blade on the latches of the needles and its relation to the slack transferred loops;

Figure 3 is a partially developed view from the outside of the needle cylinder, diagram ming the needles and some of their operating cams, the transfer bits and the latch lifter at those points of the operation where the welt loops are being transferred back to the needles and where the latch lifter is raising the latches from their fully-open position; 1

Figure 4 is a view of the transfer line of a welt made according to the prior art; while This produces an irregular and Figure 5 is a similar view of a welt transfer line made in accordance with my invention.

The invention will be shown and described in the well-known Scott 8: Williams automatic latch needle circular knitting machine adapted to make ladies hosiery with automatic inturned welt, but it should be understood that the invention may also be used in any other type of revolving needle cylinder circular machines. For an example of a Scott & Williams machine adapted to make such ladies hosiery with automatic inturned welt, reference is made to the Robert W. Scott U. S. Patent No. 1,282,958, dated October 29, 1918. In the machine shown in the drawings of the present application there is the usual needle cylinder containing a circle of independent latch needles N, N having latches 2i. The needle cylinder is of the rotary type and has the usual stationary knitting cam cylinder surrounding it. Intercalated with the needles are the usual sinkers S actuated by the outside sinker cap 300. The machine also contains the usual stitch cams 360, 3! and top center cam 351.

The sinker cap rests on the upper end of the needle cylinder but is restrained from rotating. When the needle cylinder starts to move in the reverse direction during reciprocatory knitting, the sinker cap makes a short oscillatory stroke governed by the so-called down-pick post 4M shown at the left of Fig. 1. My novel latch lifter is pivotally mounted on the sinker cap in the embodimentshownin the drawings, but it should be understood that basically my invention can also be carried out by mounting the latch lifter on a stationary part of the machine.

As shown in the above-mentioned Scott Patent 1,282,958, there is a dial D containing a transfer bit T corresponding to every other needle in the cylinder. When the transfer needles N have been drawn-down below the level of the transfer bits at the end of the making of the welt by a cam l shown at the left of Fig. 3, the transfer bits are projected outwardly between the still elevated non-transfer needles N. In this position the eyes 3 of the transfer bits are over the transfer needles N to which the loops are to be transferred. The needles N then are raised through the eyes 3 by a cam surface 2": till the needle latches are above the bits. Shortly after the lower end of the latch of each needle has cleared above its transfer bit, the bit is retracted, leaving the loop on the shank of the needle. This is the situation at the point marked 4 in Fig. 3.

These loops are transferred onto the needles at a point about in advance of the knitting or cast ofi point 1. Experience shows that some of the loops tend to ride over the ends of the latches. When this occurs and the latch subsequently closes as the regular tight loop on the aesase needle shank ridesup, the slack .transferrediloop gets under the hook of the needle and is not cast oif. On the next revolution of the machine this slack loop is again cleared below the latch and unless it happens to :ride over the end f the latch a second time, the needle will east the loop off one course later than usual. The result of this irregular casting off .to: ,prnsduoe .the ragged appearance shown in Fig. ,iI "have found means by which this irregularity can .ibe completely eliminated, giving ,the uniform .appearance to the welt shown in-'1ig.5.

I provide a. latch lifter located shortly after the point 4 at which the transfer bits retract,

leaving the .slack transfer rlQOPS on theneedles.

My llatch .lifter is .not intended to completely close the latch because the latch must be left .open ,until shortly-before .the stitch :cam .in order thatainew yarn may heilaidnnider the hook of the needle. fOn theotherghand, .it will Jbeobserved that the danger .of the .slack iloop "catch- .ing on the latch begins .as soon as ;the .needle starts .to lower. Myflatch :lifter ,plays ,a .vital ,part .in raising the latch .from .its downward, fully-open position to ,a .partially-closed iposition in the general 1neighborhoodof almrizontal di- .rection in the case of .vertioally movable needles. ,Ialsotakeadvantage-of centrifiugalforce. 'In automatic circular hosiery knitting machines when knitting in a .rotary .manner the needle cylinder turns so=fast that 11 find ailatch which has been; partly. raised will .-not return (touts-fully- ,open position. .On the other hand, .-I have no- .ticedthat, perhaps-due tosurface itension .-of oil,

centrifugal force is .often :not enough to :bring I.

the latch .upward from its fully-open position .after it is .freedfromthestitch. Therefore-my latch lifter is needed to start theimovement. -I .findthatbentrifllgal force. is .ample Jae-overcome any tendencyof .the latch :to idropaback "to .fullyopen ,position under -.the action :of gravity .after it .has .beenpartly raised ,byimy )lifter. lnifact, centrifugal force, once-started, ,tends toug en-the latch-even further. I .have found that'with lifter rall the latches will surely pass above all the loose -or slack transfer-red .loqps and :thus avoid the .undesirable appearance fshown in Fig.4.

.In the embodiment shown in .the idrawings .I have provided a circumferentially-stationarylifter blade .I-ll and l .have used descent of .the needles from .the clear leveLB :.toan intermediate level 9 to cause the-latches to-engagethe lifter .and partially raise .the latches. Thus in the drawings it will'be seen from Eigs..2 1and 3 ,that it is the descent of theneedles N, -N'--.from the clear level 8 to the intermediate level 9 which brings the needles ,into contact with the latch lifter blade. It will .be noted that rthe upper edge .H of the blade is preferably horizontal and that the blade .has considerable vertical depth. I

In view of the fact that the transferred loops arepresent on .the shanks-of vthe .needlee only at the time the weltis being .completed, the latch lifter blade need .be in operative .relation with the needles for ;a. very-limited time. Therefore I have-providedzmeans by which .this "blade ,can be moved into and out of operative relation with the .needle ,ilatches. .These .means arecontrolled fromcams I-Bil, M32 and I163 ion-the rusual gpattem drum 4.20 by a ithrustmodilfi. Thisithrust :rod conveniently can control not only the latch closing -means but also the transfer 331133. The lifiteribladeiitselfris fixed.in-.-a plate .44 mounted 4 on the upper'ifaee of the usual slnkericap 300 by a screw l5. 'This is a pivotal mounting such .that the end of the blade can be swung into and out of contact with the needles at the proper time. il -rejecting from this plate is a wire tail 46 which-extends from the plate at an angle of say g0 from the latch lifter blade. There is a tensionrspring .H attached to this tail, the other .iendio f this. spring being fastened on the sinker -...ea.-p3fl0. .Thetension spring extends in such a direction as topull the latch lifter blade into its "operativeposition'under the latches. While the springiand tail thus tend to pull the blade into its operative position, the thrust rod 462, by .meansiof a camming finger 463 on it, normally gpushes on "the wire itail 16 against "the tension spring ll 'and'thusholdstheblade away ffrom ;-the.neeclle.cylinder and the needles. This finger 14I63ihol'ds the-blade out in this manner whenever .thezthrust rod 462 is down in its" lowermost ..position .on the {pattern 'drum I 20. It will be seen .fromFigs. .1. and ,3 that ias soon asithe thrust 'ro'd ridesup on drum cam [61, the-camsurface of the ffinger 4'63 r'e1eases' the wire tail 'l6 and ".the tension spring 5 fl will 'pull'lthe latch 'llfterblade .intouits operative position. "The higher drum cam 62 raising 'thethrust .rod further willhave ;-no effect onithe latch lifter'blade because such raising of 'the thrust rod merely 1' increases "the separation between the wire tail an'dthe T'fin'ger T463. The adjustment of the machine 'is'suh that the thrust :rod 452, movingfin to beginthe operation of transferring .the "loops [2 to the needles, allows the latch lifter blade to' movef'w its operative .positio'n before any nee'dleshavin'g transferred .loops .on Ithem arrive opposite the blade. {The imeanswliich (project the transfer bits over-the transfer .needles'N are activefor .atlleast one and aihalf revolutions, and'it'will therefore "be obvious that the latch'lifterhl'ade will .be in its .operative .position xuntil after .all .the loops transferred 'to'.the"transferneedles N have passed the point where .their llatches can be affected' byjithe blade.

It 'will be noted that 'in'iFig. "2 I 'have shown only one latch at .a time 'beingra'ised by the latch-lifter blade. 'I'have found that this aids in inserting the 'blade in its operative position. It will .be understood, of "course, that other types of blades .might be used without departing "from the broad aspects .of my invention. It'1will"be noticed in .the drawings that there "is a considerable distance'betwe'en the end .oftheI'latch-lifter blade and the point where the needles "b'eglnto descend the stitch cam.

This point where .the'latchflifter hla'de ends i indicated in Fig. .3 by the .referencecharacter T5. The pointat which ,the stitchcam .beg'ins .toact on the needles is indicated .by the reference m1- meral 6, and the casting-off ,point is indicated by :the reference character "I. .It willlbe bbvious that :by .means of my invention the latches are kept from their fully-open ;-position at .the ,point 5 .by means of the latch lifter lblade. Thereafter until after the needles have passed .point 6 they continue to (he held :up from their .lowermost position and out of danger .from @contact with-theslackloops by centrifugal'foree.

When the --1lhIillSl'/?1.0d .462 off iits'cams at the end of "the transfer-operation, thev camming .surfacenf the finger tGS-avillpush on the wire tail lli causing the :latch lifter blade m tohe swun radially outward away -from -the needles and needle cylinder.

In circular knitting machines the sinker map 306 has an oscillatory movement when knittin heel and toe pockets. During rotary knittin the sinker cap is held in one extreme of its oscillation by the usual down-pick post 40! (see Fig. 1). But each time the machine starts to knit in the reverse direction (clockwise as it appears in Fig. 1), the cap has a limited radial movement. The pivot screw is of the plate I4 carrying the latch lifter blade is so located with respect to the forward knitting cams of the needles and the thrust rod 462 that the interaction of blade and needle latches heretofore described is effective when the sinker cap is turning in its forward direction but not inits reverse direction. While the sinker cap is making its limited oscillation on a reverse movement of the needle cylinder, the wire tail It is a short distance away from the camming surface of the finger 463. The spring l'l therefore holds the latch lifter blade in its operative position. There is danger, as the sinker cap approaches the end of its reverse movement, that the latch lifter blade will come in damaging contact with the needles and break them. To avoid this danger, I provide an element on a stationary part of the machine adapted to push on the plate It to move the blade out of action. This ele-- ment is a finger i8 mounted on the dial drivin shaft post I!) carrying the dial drive gear. The finger is stationary. As soon as the sinker cap returns to its rotary or forward position, the plate and blade will be released from this finger to the control of the thrust rod 562. It will be obvious that, if desired, I can mount the plate and blade on a stationary part of the machine.

I also find it convenient to provide a short control finger 20 on the plate so that the latch lifter blade can be swung out of operative position by hand.

It will be seen that the wire tail l6 and camming finger 463 keep the blade out of action during rotary knitting except just prior to, during and immediately following loop transfer, and that the finger IS on the stationary part of the machine holds the latch lifter blade out of action during knitting in the reverse direction. These two means cooperate so that one is effective during knitting in the forward direction and the other during knitting in the reverse direction, each releasing control to the other at the proper time.

While the invention is peculiarly useful in connection with transferred stitches, it will be obvious that partial closing of the latches and maintaining them partially raised by centrifugal force, can also be used in non-transfer knitting.

I claim:

1. An automatic stocking knitting machine having a rotary circle of independent needles with pivoted latches and a stitch cam for easting loops off the needles, in combination with latch lifting means comprising a blade adapted to be moved to and from an operative position at or near the shanks of the needles to raise latches to a position not substantially above the horizontal position and only partially toward closed position during and after the transfer, and means to control the position of the latch lifting means.

2. A circular stocking knitting machine according to claim 1 in which the blade when in its operative relation with the needle latches is a time, whereby the blade can be freely moved into and out of operative position under the latches.

3. A circular stocking knitting machine having a rotary circle of independent needles with pivoted latches, bits to transfer loops to the needles as the latter rise through the eyes of the bits, means to operate the bits and a stitch cam for casting loops off the needles, in combination with latch lifting means comprising a blade adapted to be moved to and from an operative position at or near the shanks of the needles to raise latches only partially toward closed position during and after the transfer, and means adapted to control both the transfer bits and the latch lifting means.

4. A circular stocking knitting machine adapted to make an automatic turned welt, said machine having a needle cylinder, a circle of independent needles and independent sinkers therein, a latch lifter blade pivotally mounted on the machine to swing toward and away from the needle cylinder, and means urging the blade toward the cylinder, in combination with a thrust rod controlling the transfer of loops at the welt, and means actuated by the thrust rod holding the blade out of action during rotary knitting except just prior to, during and immediately following welt transfer.

5. A circular stocking knitting machine adapted to make an automatic turned welt, a needle cylinder having therein a circle of independent latch needles and independent sinkers and a sinker cap, latch lifting means in which there is a blade pivotally mounted on the sinker cap, a spring associated with the blade tendin to push it into its operative position, a thrust rod adapted, when lowered, to hold the blade out of action, means to raise the thrust d for transferring stitches, the parts being so arranged that oscillation of the sinker cap during knitting in the reverse direction releases the ting, the latch lifter blade being pivotally mounted on the sinker cap, and the means to control the position of the latch lifting means including means tending to pivot the blade into its operative position and two means tending to pivot the blade out of its operative position, one effective for knitting in the forward direction and the other in the reverse direction, the forward means being adapted to release its conblade from the thrust rod, and an element on a stationary part of the machine adapted to push the blade out of action when the sinker cap is thus oscillated.

6. A circular stocking knitting machine according to claim 1 in which there is a needle cylinder containing a circle of needles adapted to turn in both the forward and reverse directions, a circle of independent sinkers in the cylinder and a sinker cap having a limited oscillatory movement on change of direction of knittrol during forward knitting when loops are to be transferred.

7. An automatic circular knitting machine having a rotary circle of independent needles with pivoted latches, bits to transfer loops to the needles as the latter rise through the eyes of the bits, means to operate the bits and a stitch cam for casting loops off the needles, in combination with a latch lifter ahead of and circumferentially spaced from the stitch cam and adapted to partially raise the latches of the needles, said machine being adapted to roadapted to engage only one or two latches a 7 5 tate at such a speed that the latches do notdrop assume down after 'leavingithe lifter, wherebyitheztrans ferred loops :on ithe sshanks f the :needles 2,118 prevented from getting into the hooks ref ithe "needles.

*8. An automatic circular knitting machine having a .rotary ricircle of "independent needles =with pivoted latches, bits "adapted to transfer loops-:to the needles as the latter rise through f the eyes of the bits, cam rmeanszadapted -120 lower needles to an intermediate level from :a first :level where the loops :were transferred to the needles :below tithe latches, and a stitch roam adapted rto 'lower the .needles from the illiter- :mediate :level to :cast offthe loops, in combination withialatch lifter effective cnly duringithe lowering of the needles toithe intermediateilevel (to partially raise the latches to a position not substantially above horizontal position, :whereby the .transferred loops are prevented from gettin into thehooks of the needles.

-9.:"An automatic circular lznitting machine having a rotary circle of independent needles with pivoted latches and a stitch cam:for..cast- -ing loops 401T the needles, in combination (with -.a .latchllfter spaced some distance. ahead f the sstitchicam adapted :to move all the Jiully-open llatches of passing needles less than 90I-to'\va1"d closure; whereby any stitches on the-shanks 0f the needles below the latchesarerprevented from catching on ithe latches while "the :needles are a travelling from the lifter to theiStitch cam and 'the latches are left ropen suinciently to prevent interference with yarn Jbeing'ied to the needles.

'10. An automatic circular knitting .machine having a rotary circle :of independent needles with pivoted latches, astitch cam for casting loops oif .the needles and a latch lifter spaced some distance ahead :of I the 'stitch cam adapted :toraise theilatches of passing nee'dlesless than 90 to approximately the horizontal position, said circle of needles being'a'daptedsto rotate at such .-:a speed that 1 the latchcsdonot -dropdown after leaving the lifter; whereby any stitches on the shanks of the needles below the latches are prevented from catching 'on thellatches-while the needles .are travelling Jfroml'the lifter 130 the stitch cam and the latches are'left sufliciently open 'to prevent interference With yarn bein f ed to. the :needles.

1 1. An automatic circular knitting machine "having a rotary circle of independent mee'dles with pivoted latches, a stitch cam .for casting loops ofithe needles and a cam spaced some distance ahead or thestitch cam adapted to move needles vertically, in combination With-a latch lifter also spaced somedistance ahead of the s'titch cam adapted to raise thedatch'es ofspass- .ing needles'less thanl90 toward closureras the needles leave such advance cam; wherebyany stitches ontthe shanks :of 'the;need1es':below::the latches are prevented from catching 'on the latches while the needles-are travelling .frointthe lifter to the stitch cam and thelatches -are -left sufiiciently open to prevent interference with yarn being fed to the needles. 7

l2. An automatic circular knitting machine having a rotary circle of independent needles with pivoted latches, and astitch cam 'for-casting loops oii the needles, in combination with a latch li'fterspaced some 'distanceahead oi the stitch -cam adapted to raise the" latches of *passing needles less than 90 and release them-near the horizontal position,-said latch lifter-also"be ing adapted to keep under it any loops-on the shanksof passing needles, andmeans 'adaptewto cii :move th'e litter automatically .into :and dllt of operative relation with the ;needle latches; "whereby any loops transferred :to the shanks of the needles :in advance of the stitch loam are prevented from gettingiin'to the-"needle hooks.

'13. methodo'f :operating anautomatic cirolilar knitting:machine having a rotating circle =of latch needles, astitchcam and a latch litter, in which there :are at least :the step of liftin the :needle latches less :than to partially 'elose'diposition by means'of the lifter and the step -"df rotating =the needles in the needle .circle "for azdis'tancei-afterileaving the lifter and :before rea ':hingathe stitchncam and during that'distance -preventing the-latches from returning lto =fullyopen position'by centrifugal force, and there- "aiter castingo'fi loops-on the needlevshanksi-by means of the stitch 0am, whereby the "loops on the :needle shanks are .prevented from gettin into the hooks oi the needles.

14. A method of -operating an automatic :cir-

-cular :knitting ,machine having latch needles, .'a

latch lifter and transfer bits, in which fthere are 4 at least' the steps of transferring loops ifrom the bits 'to themeedles-belowthe late-hes while the? latches areopen, lowering the :needles hav- "ing the trans'ferred loops to anlintermediate level while simultaneously-positivel-y lifting the latchcs I part way from their fully-open position by means :or the lowering and the latch :lifter, and thereafter rotating themachine at such -a speed "that -the latches are prevented by centrifugal force from returning to fully-open position and thereafter lowering the :needles further tocast "'ofi the loops, whereby the transferred loops do not get caught under the hooks of the needles.

-1 5. A method of transferring'iloops -on an-automatic circular knitting machine havingin'de- "pendent latch needles -a latch liiter and transfer bits comprising the steps of transferring loops "from thebits-to then'eedles; raisingathe needles to -clear level, then lowering "them :to 'an interme- "diatelevel which simultaneously positively.lit ing up the L-latc'hcs "part wayon 'the .latch .lifter, allowing the needles to 1 travel ;at that intermediate level, and thereatter :"feeding yarn and drawing the zneedles down a :stitch oam tolc'ast 'off the transferred sleeps :andniraw mew :loops, -=where'by the =s'la'ck transferred' loops :cio not set *caug'htinthehooks'ofthe needles.

f6. *A- method dfntransferring Lloops 'on 581M811- tomatic circular knitting machinelaccqrdhigrtn claimi15' in which after the latches are raised up part way the needles con'tinue at that intermediatei-levlfor a time beyond the latch lifter with the latches held up mycentrifugal (force before. the needlesego down-the stitch cam, w'herebyithe latches remain above the reach of the slack loops for the entire period from transfer t stitch 0am. 

